Contemporaneous broad-band photometry and Hα\alpha observations of T Tauri stars

The study of contemporaneous variations of the continuum flux and emission lines is of great importance to understand the different astrophysical processes at work in T Tauri stars. In this paper we present the results of a simultaneous $BVRI$ and H$\alpha$ photometric monitoring, contemporaneous to medium-resolution spectroscopy of six T Tauri stars in the Taurus-Auriga star forming region. We have characterized the H$\alpha$ photometric system using synthetic templates and the contemporaneous spectra of the targets. We show that we can achieve a precision corresponding to 2$-$3 \AA\ in the H$\alpha$ equivalent width, in typical observing conditions. The spectral analysis has allowed us to determine the basic stellar parameters and the values of quantities related to the accretion. In particular, we have measured a significant veiling only for the three targets with the strongest H$\alpha$ emission (T Tau, FM Tau, and DG Tau). The broad-band photometric variations are found to be in the range 0.05$-$0.70 mag and are often paired to variations in the H$\alpha$ intensity, which becomes stronger when the stellar continuum is weaker. In addition, we have mostly observed a redder $V-I$ and a bluer $B-V$ color as the stars become fainter. For most of the targets, the timescales of these variations seem to be longer than the rotation period. One exception is T Tau, for which the broad-band photometry varies with the rotation period. The most plausible interpretation of these photometric and H$\alpha$ variations is that they are due to non-stationary mass accretion onto the stars, but rotational modulation can play a major role in some cases.Comment: 21 pages, 11 figures, accepted for publication in Acta Astronomic

El pensamiento en la clase de inglés: fuente de poder o vulnerabilidad

The students’ thoughts are a source of power when they are used correctly in the EFL classroom, but, on the contrary, they may be an obstacle to learning and cause emotional instability if the students do not use them well. According to general studies of psychology, thoughts can be classified as relevant and irrelevant. A relevant thought takes place when a person dedicates his thinking to a specific task. For instance, a student is doing a multiple-choice exercise about phrasal verbs, and makes hypothesis and deductions from his knowledge of phrasal verbs in order to do the exercise. Then, as those relevant thoughts take place, other thoughts that are not related directly to that exercise emerge. Those can be irrelevant thoughts when they do not help in doing the task, and interfere with relevant thoughts. They refer to intrapersonal matters, as self-efficacy, motivation, self-esteem, etc. For instance, the student thinks: “I won’t be able to do the exercise” or “I should have studied harder”, etc. However, these irrelevant thoughts can be facilitating to the task if the student is able to analyze those thoughts and change them into positive ones: “I will do my best” or “Although I have not studied hard, I will give it a chance” .This paper shows how cognition and emotion relate to each other and how relevant and irrelevant thoughts are created. It will also explain how the language learner employs self-defense mechanisms as s/he finds difficulties or aversion in doing learning tasks. As a general consideration, irrelevant thoughts can be as important as relevant thoughts in learning a language. Moreover, many researchers claim that they are responsible for determining success or failure in ordinary classroom learning tasks

Una forma de reducir la ansiedad en los exámenes orales de inglés como lengua extranjera: técnica de reevaluación positiva

This paper deals with a research project, which aims to analyze the application of a technique in order to reduce anxiety in foreign language oral exams. After considering reasons for the existence of exam anxiety and some options for anxiety reduction, the technique of positive reevaluation is described and presented as a possible alternative. An empirical study carried out with secondary-school students showed reduction of anxiety when using this technique.The study attempts to verify the hypothesis that anxiety levels drop when candidates, who perceive the oral exam negatively, reevaluate their own performance at the start of the exam and succeed in perceiving it positively. To facilitate this, examiners model their discourse at the very beginning of the oral exam, providing candidates with comprehensible input and the opportunity to reduce their anxiety

On the accretion properties of young stellar objects in the L1615/L1616 cometary cloud

We present the results of FLAMES/UVES and FLAMES/GIRAFFE spectroscopic observations of 23 low-mass stars in the L1615/L1616 cometary cloud, complemented with FORS2 and VIMOS spectroscopy of 31 additional stars in the same cloud. L1615/L1616 is a cometary cloud where the star formation was triggered by the impact of the massive stars in the Orion OB association. From the measurements of the lithium abundance and radial velocity, we confirm the membership of our sample to the cloud. We use the equivalent widths of the H$\alpha$, H$\beta$, and the HeI $\lambda$5876, $\lambda$6678, $\lambda$7065 \AA$$emission lines to calculate the accretion luminosities, $L_{\rm acc}$, and the mass accretion rates, $\dot M_{\rm acc}$. We find in L1615/L1616 a fraction of accreting objects ($\sim 30\%$), which is consistent with the typical fraction of accretors in T associations of similar age ($\sim 3$ Myr). The mass accretion rate for these stars shows a trend with the mass of the central object similar to that found for other star-forming regions, with a spread at a given mass which depends on the evolutionary model used to derive the stellar mass. Moreover, the behavior of the $2MASS/WISE$ colors with $\dot M_{\rm acc}$ indicates that strong accretors with $\log \dot M_{\rm acc} \gt -8.5$ dex show large excesses in the $JHK{\rm s}$ bands, as in previous studies. We also conclude that the accretion properties of the L1615/L1616 members are similar to those of young stellar objects in T associations, like Lupus.Comment: Accepted by Astronomy and Astrophysics. 17 pages, 11 figures, 6 table

A WFI survey in the Chamaeleon II dark cloud

We present the results of an optical multi-band survey for low-mass Pre-Main Sequence (PMS) stars and young Brown Dwarfs (BDs) in the Chamaeleon II (Cha II) dark cloud. This survey constitutes the complementary optical data to the c2d Spitzer Legacy survey in Cha II. Using the Wide-Field Imager (WFI) at the ESO 2.2m telescope, we surveyed a sky area of about 1.75 square degrees in Cha II. The region was observed in the Rc, Ic and z broad-bands, in H-alpha and in two medium-band filters centered at 856 and 914 nm. We select PMS star and young BD candidates using colour-magnitude diagrams (CMDs) and theoretical isochrones reproduced ad-hoc for the WFI at the ESO2.2m telescope system. The selection criteria are also reinforced by using the previously known PMS stars in Cha II to define the PMS locus on the CMDs and by investigating the infrared (IR) colours of the candidates. By exploiting the WFI intermediate-band photometry we also estimate the effective temperature and the level of H-alpha emission of the candidates. Our survey, which is one of the largest and deepest optical surveys conducted so far in Cha II, recovered the majority of the PMS stars and 10 member candidates of the cloud from previous IR surveys. In addition, the survey revealed 10 new potential members. From our photometric characterisation, we estimate that some 50% of the 20 candidates will result in true Cha II members. Based on our temperature estimates, we conclude that several of these objects are expected to be sub-stellar and give a first estimate of the fraction of sub-stellar objects.Comment: 26 pages, 18 figure

UNA FORMA DE REDUCIR LA ANSIEDAD EN LOS EXÁMENES ORALES DE INGLÉS COMO LENGUA EXTRANJERA: TÉCNICA DE REEVALUACIÓN POSITIVA

AbstractThis paper deals with a research project, which aims to analyze the application of a technique in order to reduce anxiety in foreign language oral exams. After considering reasons for the existence of exam anxiety and some options for anxiety reduction, the technique of positive reevaluation is described and presented as a possible alternative. An empirical study carried out with secondary-school students showed reduction of anxiety when using this technique.The study attempts to verify the hypothesis that anxiety levels drop when candidates, who perceive the oral exam negatively, reevaluate their own performance at the start of the exam and succeed in perceiving it positively. To facilitate this, examiners model their discourse at the very beginning of the oral exam, providing candidates with comprehensible input and the opportunity to reduce their anxiety

Hunting for brown dwarf binaries and testing atmospheric models with X-Shooter

The determination of the brown dwarf binary fraction may contribute to the understanding of the substellar formation mechanisms. Unresolved brown dwarf binaries may be revealed through their peculiar spectra or the discrepancy between optical and near-infrared spectral type classification. We obtained medium-resolution spectra of 22 brown dwarfs with these characteristics using the X-Shooter spectrograph at the VLT. We aimed to identify brown dwarf binary candidates, and to test if the BT-Settl 2014 atmospheric models reproduce their observed spectra. To find binaries spanning the L-T boundary, we used spectral indices and compared the spectra of the selected candidates to single spectra and synthetic binary spectra. We used synthetic binary spectra with components of same spectral type to determine as well the sensitivity of the method to this class of binaries. We identified three candidates to be combination of L plus T brown dwarfs. We are not able to identify binaries with components of similar spectral type. In our sample, we measured minimum binary fraction of $9.1^{+9.9}_{-3.0}$. From the best fit of the BT-Settl models 2014 to the observed spectra, we derived the atmospheric parameters for the single objects. The BT-Settl models were able to reproduce the majority of the SEDs from our objects, and the variation of the equivalent width of the RbI (794.8 nm) and CsI (852.0 nm) lines with the spectral type. Nonetheless, these models did not reproduce the evolution of the equivalent widths of the NaI (818.3 nm and 819.5 nm) and KI (1253 nm) lines with the spectral type.Comment: Accepted for publication in MNRA

EL PENSAMIENTO EN LA CLASE DE INGLÉS: FUENTE DE PODER O VULNERABILIDAD

AbstractThe students’ thoughts are a source of power when they are used correctly in the EFL classroom, but, on the contrary, they may be an obstacle to learning and cause emotional instability if the students do not use them well. According to general studies of psychology, thoughts can be classified as relevant and irrelevant. A relevant thought takes place when a person dedicates his thinking to a specific task. For instance, a student is doing a multiple-choice exercise about phrasal verbs, and makes hypothesis and deductions from his knowledge of phrasal verbs in order to do the exercise. Then, as those relevant thoughts take place, other thoughts that are not related directly to that exercise emerge. Those can be irrelevant thoughts when they do not help in doing the task, and interfere with relevant thoughts. They refer to intrapersonal matters, as self-efficacy, motivation, self-esteem, etc. For instance, the student thinks: “I won’t be able to do the exercise” or “I should have studied harder”, etc. However, these irrelevant thoughts can be facilitating to the task if the student is able to analyze those thoughts and change them into positive ones: “I will do my best” or “Although I have not studied hard, I will give it a chance” .This paper shows how cognition and emotion relate to each other and how relevant and irrelevant thoughts are created. It will also explain how the language learner employs self-defense mechanisms as s/he finds difficulties or aversion in doing learning tasks. As a general consideration, irrelevant thoughts can be as important as relevant thoughts in learning a language. Moreover, many researchers claim that they are responsible for determining success or failure in ordinary classroom learning tasks

Variability of the transitional T Tauri star T Chamaeleontis

We characterize the physical properties of T Chamaeleontis, a transitional T Tauri star showing UX Ori-type variability, and of its associated disc, and probe possible effects of disc clearing processes. Different spectral diagnostics are examined, based on a rich collection of optical high- and low-resolution spectra. We determine radial and projected rotational velocities, and measure equivalent widths of the Li I (6708 A) line and of the most prominent emission lines (e.g. Ha, Hb and [OI] 6300A); we analyse shape changes of photospheric lines via bisector-method, while variability in Ha and Hb is inspected through line-profile correlation matrices. The strength of the Ha and Hb emission is highly variable and well correlated with that of the [OI] lines, as well as with Av variations of over three magnitudes. Variations up to nearly 10 km/s in the radial velocity of the star are measured on analogous time-scale, but with no apparent periodicity. SED modelling confirms the existence of a gap in the disc. Variable circumstellar extinction is pointed out as responsible for the conspicuous variations observed in the stellar continuum flux and for concomitant changes in the emission features by contrast effect. Clumpy structures, incorporating large dust grains and orbiting the star within a few tenths of AU, obscure episodically the star and, eventually, part of the inner circumstellar zone, while the bulk of the hydrogen lines emitting zone and outer low-density wind region traced by the [OI] remain unaffected. Coherently with this scenario, the detected radial velocity changes are also explainable in terms of clumpy materials transiting and partially obscuring the star.Comment: 38 pages, 32 figures. To appear in the Astronomy and Astrophysics main journa

Aligning the principles of assessment for learning to learning in physical education: a review of literature

peer-reviewedThe full text of this article will not be available in ULIR until the embargo expires on the 19/04/2022Background: A comprehensive international literature review on alternative assessment in physical education has been provided by López-Pastor et al. ([2013]. “Alternative Assessment in Physical Education: A Review of International Literature.” Sport, Education & Society 18 (1): 57–76). The authors remarked that while more authentic forms of assessment in physical education have been evidenced over the last three decades, the extent to which alternative assessment practices have become common practice in the teaching of physical education is yet to be established. Purpose: This review provides an updated perspective on the prevalence of assessment for learning (AfL) principles in physical education discourse since the 2013 publication. The intent is to inform and consider future AfL practices in school physical education and physical education teacher education (PETE) programmes. Methods: Eligibility criteria for the review required full-text articles written in English or Spanish; published (open access and/or in print) in peer-reviewed, academic and professional journals; and limited to the period 2013–2019. Inclusion criteria required articles to report assessment being used to promote learning in physical education, regardless of making reference to ‘assessment for learning’. Findings: Fifty-two articles met the inclusion criteria. A thematic analysis of these articles resulted in four themes: i) traditional positioning of assessment in physical education; ii) AfL and physical education; iii) the constraints in enacting AfL in physical education; and iv) how to most effectively embed AfL in daily physical education practices. Conclusions: The main conclusions of this review are that i) AfL is a learning-oriented assessment based on socio constructivist theories and integrated into the teaching-learning process, ii) physical education teachers continue to use assessment solely to grade students; iii) physical education teachers do not have the necessary skillset to use AfL in physical education successfully; iv) physical education teachers need to be supported to implement AfL; and v) it is necessary to consider how best PETE programmes can infuse AfL across the programme